1. Field of the Invention
The present invention relates to an engine control device. More particularly, to an engine control device for detecting a totally closed throttle valve and determining an amount of fuel supply on the basis of an opening of the throttle valve with reference to the detection signal.
2. Description of Background Art
On determining an amount of fuel supply of an internal combustion engine, there is known a control device (Japanese Published Unexamined Application No. 11-343901) in which an increase correction value of the amount of fuel supply is different between when a throttle opening is increased from a totally-closed position of a throttle valve and when the throttle opening is increased from any other position than the totally-closed position.
On the other hand, there is known an engine having a fast idle mechanism in which during warming up, a minimum opening of the throttle valve is mechanically made large to increase the idle speed. In such an engine, the actual opening of the throttle valve is different between during a fast idle operation and during a normal idle operation after warming up. Thus, there has been proposed a throttle valve totally closed detection device (Japanese Published Unexamined Application No. 56-107926) capable of detecting, even though a difference in opening during idling as described above, the minimum opening (totally closed) at that time.
In this device, there is provided means for storing the minimum value for an opening detection signal of the throttle valve, and when an error or a new value of the opening detection signal within a range of a predetermined dead zone falls short of a stored value, the above-described minimum value is replaced with the new value of the opening detection signal. According to this totally closed detection device capable of renewing the totally closed position of the throttle valve, the totally closed position can be detected irrespective of operation during fast idling or during normal idling.
In the opening of the throttle valve indicating the totally closed position, there is provided a dead zone, and when the throttle valve is opened with this dead zone exceeded, it is judged that the driver has performed an operation for acceleration. In an engine having the fast idle mechanism, there is set a dead zone which has been enlarged to a large opening corresponding to the fast idle. In the case where the dead zone has been enlarged to the fast idle region as described above, the throttle opening cannot be detected within this range of the dead zone, and therefore, it cannot be judged whether the throttle valve is opened by the driver or the throttle valve is opened by a fast idle mechanism.
It is an object of the present invention to solve the above-described problems, and to provide, in an engine having the fast idle mechanism, an engine control device capable of accurately judging a fully-closed state of the throttle valve.
In order to achieve the above-described object, according to a first feature of the present invention, there is provided an engine control device having a manual opening and closing means and an automatic opening and closing means of a throttle valve, in which a throttle opening indicated value for the automatic opening and closing means is a value obtained by adding, to a totally closed reference value, a water temperature correction value, that is a function of engine cooling water temperature, and an atmospheric pressure correction value, that is a function of the atmospheric pressure. The engine control device has a throttle opening detection means for detecting the throttle opening. Wherein a value obtained by subtracting the water temperature correction value and the atmospheric pressure correction value from an actual opening to be detected by the throttle opening detection means is set to a totally closed value of the throttle opening.
According to the first feature, even when the throttle valve is operated by the automatic opening and closing means in the control of the engine, the totally closed value is judged by a value obtained by subtracting the water temperature correction value and the atmospheric pressure correction value from the actual opening. Therefore, even when the throttle valve is operated by the automatic opening and closing means, the dead zone concerning the totally closed value can be maintained small.
Also, according to a second feature of the present invention, there is provided an engine control device wherein when a dead zone concerning the totally closed value is set and the value obtained by subtracting the water temperature correction value and the atmospheric pressure correction value from the actual opening goes out of the dead zone, there is provided a renewal means for replacing the totally closed value with the value obtained by subtracting the water temperature correction value and the atmospheric pressure correction value from the actual opening.
According to the second feature, when renewing the totally closed value in consideration of deterioration with time and the like, it is possible to perform a renewal by sensing a change in the total closeness due to a slight deterioration because the dead zone for renewal concerning the totally closed value can be used while it is made small.
Also, according to a third feature of the present invention, there is provided an engine control device wherein when the value obtained by subtracting the water temperature correction value and the atmospheric pressure correction value from the actual opening continues for a scheduled renewal time period to go out of the dead zone, the renewal means is constructed to renew the totally closed value. According to the third feature, it is possible to prevent the totally closed value from being renewed by detecting an instantaneous change in the totally closed state.
Further, according to a fourth feature of the present invention, there is provided an engine control device wherein fuel increase correction values are set which are different from each other between when the opening is increased from the totally closed position and when the opening is increased from any other position than the totally closed position. The present invention corrects the reference amount of fuel supply by using the fuel increase correction value. According to the fourth feature, the reference amount of fuel supply can be corrected on the basis of a correct totally closed value to be detected.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.